A colleague of mine, a geriatric social worker, likes to tell a story about the time one of his clients, an 86-year-old woman, failed to answer the phone for their daily chat. Worried about her safety, he ran to her building and asked the superintendent to let him into the apartment. Opening the door, he found a trail of lit candles and burning incense that led to the master bathroom. His client, it turned out, had a visitor.

The intimate lives of older people make us squeamish and anxious, especially in a culture so focused on beautiful young bodies primed for physical pleasure. We prefer to think that older people are asexual, resigned to a certain loss of desire and vitality. Nor do our traditions provide much guidance. In the Bible, Sarah and Abraham were age 90 and 100, respectively, when God told them they would have a son—and Sarah, famously, laughed at the news. In the opening scene of Plato’s “Republic,” an old man approvingly cites the poet Sophocles, who declared his relief, late in life, at being free of the “frenzied and savage master” of sex.

At a time when almost every kind of physical intimacy is discussed with increasing candor, the erotic feelings of empty nesters, retirees and the residents of assisted-living centers remain a taboo subject, except in tiresome jokes about Viagra. But there is nothing unusual or deviant about romance among older people. If we have learned nothing else from the past half-century of personal freedom and experimentation, it is that we are profoundly sexual beings. How we understand ourselves over the course of a lifetime is closely tied to our bodies and how we share our bodies with others, even when we’re done reproducing. The details may change with age, but our basic physical and psychological needs do not.

A growing body of research on aging suggests that many older Americans have satisfying sexual relationships well into their later years. The largest systematic study, published in the New England Journal of Medicine in 2007, involved just over 3,000 subjects. It found that, although sexual activity does decline with age, about half of individuals between the ages of 65 and 74 remain active, as do 26% of those between 75 and 85. Among those in this second group, 54% said that they had sex at least two or three times a month, and 23% reported relations with a partner at least once a week.

Keep in mind, too, that this is no small population. According to estimates by the U.S. Census Bureau, there were some 34 million Americans in these two groups (age 65 to 84) in 2010. Twenty years from now, as the ranks of older Americans are swelled by aging baby boomers, that number is expected to grow to approximately 62 million. And as we know, this will be a generation that has grown up more preoccupied with sex than perhaps any generation before it.

The New England Journal of Medicine study found that poor health was not the main reason that older people abstain from physical intimacy. Loss of desire is also not nearly as common as our popular culture would have us believe. Ranking high among the impediments, especially for women, is the absence of a willing and/or able partner. In fact, most of the women who cited health problems as the reason for their sexual inactivity were referring not to their own problems but to those of their spouses.

Medical problems that interfere with sex, like mobility-limiting arthritis, do become more common over the years. But other problems, such as premature ejaculation in men and dyspareunia (pain during intercourse) in women, actually become less common with advancing age. Despite the picture painted by television commercials for drugs that deal with erectile dysfunction, the majority of men, even in the oldest age groups, reported having little difficulty in that department.

The deeper problem with the advertisements for Viagra, Cialis, and their competitors is the image that they create of healthy intimacy for older people. The marketing depicts a utopian version of sex, in which the best and only valid sort of activity involves a fit, extremely attractive couple who segue seamlessly from doing the dishes to their bedroom.

These idealized, and mostly unobtainable, scenarios ignore much of what we have learned about the reality of romantic activity among older partners. Many professionals who deal with these issues report high degrees of satisfaction among the people in their care, even when the relationships involve alternative approaches to intimacy.

Sometimes these more limited activities are dictated by medical conditions, like hip arthritis that makes traditional intercourse impractical. Other times, it is simply a matter of the couple’s preferences.

And who’s to say what’s “normal” for older people if it brings satisfaction to them? Here it is useful to make a comparison to another area of health. As many of us have discovered for ourselves, nearsightedness is nearly universal after the age of 40. Yet no one would call those of us with glasses or contact lenses “abnormal.” These are merely age-appropriate adjustments that make it possible for us to see.

Why should sexuality be viewed any differently as we get older? We simply need to adapt our attitudes and techniques. It is a disservice to older people, as well as to those of us approaching those years, to view any form of safe sexual expression that persists into later life as anything but healthy.

Unfortunately, the unwitting conspirators in creating the taboos that surround these issues are often doctors. In the New England Journal of Medicine study, only 38% of men and 22% of women reported having discussed sex with a physician since turning age 50. Fifty? In the geriatric facilities where I work, 50 is the equivalent of the newborn nursery.

These findings are jarring not only because of the quality-of-life issues that are going unaddressed, but also because they have real health consequences. A modest proportion of new HIV infections are now occurring in people over the age of 50. In one study of single, sexually active women over the age of 50, less than half reported that their partners used condoms.

Changing our approach to the romantic lives of older Americans will not be easy. It presents a variety of new challenges, especially for professionals in my field. My own introduction to the barriers we face came many years ago, when two of my older widowed patients decided to get married. They had met at a nursing home where they were both patients, and neither had any sort of dementia that would interfere with their capacity to consent. After the wedding, they simply became roommates. Their sexual relationship was their own business.

But what about residents of nursing homes or assisted-living centers who are not married, not roommates, or have a compromised ability to consent? This poses such thorny issues that most facilities have simply discouraged residents from pursuing intimate relationships.

Fortunately, a number of facilities have started to recognize that a nursing home is a home first and a health-care facility second. The Hebrew Home for the Aged in Riverdale, N.Y., for example, actually promotes healthy romantic relationships among residents. The home’s policies specifically note that “residents have the right to seek out and engage in sexual expression, including words, gestures, movements or activities that appear motivated by the desire for sexual gratification.” Staff members are also taught to recognize when cognitive impairment might preclude such relationships and how to intervene with couplings that are not consensual.

These issues have assumed special urgency over the past several decades. A mountain of recent research has shown that not only is life expectancy rising in the U.S., but more people are spending the last years of their lives without the burden of immobilizing disabilities. These encouraging trends will continue for the foreseeable future, but we have yet to think seriously about what our extended lives mean for our personal identities, our families and our society. We have not gotten past the idea that our final decades are a problem to endure, rather than an opportunity for new experiences and personal bonds.

I’m not a Pollyanna about aging, and I’m well acquainted with the details of our physiological twilight. But we need to recognize the profound benefits of growing older in 21st-century America. Spouses in marriages that endure into late life report some of the highest levels of marital satisfaction and the lowest rates of divorce. As we age, many of the constraints that made us anxious and unhappy when we were younger—juggling work and family responsibilities, dealing with difficult bosses and colleagues, fretting about career success—slip away, and we enjoy a newfound freedom. We are liberated to cultivate ourselves and the relationships that matter most to us. And if we find ourselves alone, we can form new bonds and find new loves.

There are many erroneous stereotypes about getting older. As we age, we tend to get treated like a number rather than like individuals with a wide range of preferences and abilities. Among the worst of these tendencies is the assumption that after the age of, say, 60, we should simply forget about physical intimacy.

With luck (and with the help of our ever more sophisticated medical technologies), those of us now in the middle years of life will be the “dirty” old men and ladies of tomorrow. In the meantime, we must struggle to overcome the habits and taboos that now interfere with the happiness of so many older people. There is nothing “dirty” about the sexual feelings that attend our lives from adolescence on. The great irony of ageism—and what sets it apart from other forms of prejudice—is that you eventually become the target of your own bigotry. We must begin to approach aging with the honesty and wonder that it deserves.

Mark Lachs is director of geriatrics for the New York-Presbyterian Healthcare System and a professor of clinical medicine at the Weill Cornell Medical College.